The Art of Divine Contentment

Thomas Watson is one of the most famous Puritan preachers in history, and his writings during the 17th century are still read across the world today. He was a prodigious writer whose works include All Things for Good (originally published as A Divine Cordial), The Ten Commandments, and more.
The Art of Divine Contentment is a study of one of Paul's letters to the Philistines, and the notion that being discontent is a sin. As part of the answer, Watson suggests, "The way for a man to be contented is not by raising his estate higher, but by bringing his heart lower."